Metabolism must be coupled with developmental transition to fulfill the energy requirements during an organism’s life cycle. In most animals, steroid hormones are crucial regulators of life-stage ...transitions until adulthood. In the fruit fly Drosophila, ecdysteroid titers drive developmental transitions, such as molting and metamorphosis 1–4. Although the timings of molting and larval-pupal transition are dependent on environmental and internal conditions, metamorphosis is a temporally controlled life transition event that solely relies on energetic macromolecules accumulated during the larval period. The ecdysteroid signaling cascade and the energetics of metamorphosis have been determined 5–8. However, the molecular mechanisms that regulate metabolic homeostasis during metamorphosis remain largely unknown. Here, I show that the programmed regulation of carbohydrate metabolism by steroid hormones directs the prepupal-pupal transition in Drosophila. I found that pupation is associated with a transient increase in glucose oxidation. Mechanistically, after pupariation, ecdysteroid signaling and the competence factor Ftz-F1 regulates the systematic degradation of circulating trehalose via the transient induction of trehalose transporters and trehalase (Treh) in a timely manner. Trehalose metabolism is crucial for energy homeostasis at the prepupal-pupal transition. Moreover, trehalose catabolism acts upstream of ecdysteroid biosynthesis and signaling. My findings lead to the hypothesis that trehalose breakdown not only defines energy costs by providing a carbon source but also facilitates pupation by inducing water loss in the puparium. My work sheds light on the ways in which a life-stage transition is driven by the preprogrammed coordination between steroid hormones and catabolism of stored nutrients.
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•Pupation is associated with an increase in glucose oxidation•Glucose metabolism is crucial for energy homeostasis at prepupal-pupal transition•Trehalose catabolism acts upstream of ecdysteroid biosynthesis and signaling•Ecdysteroid signaling directs the programmed trehalose catabolism after pupariation
The development of animal body structures requires the temporal coordination of systemic hormonal signaling and metabolic homeostasis. Nishimura reveals that metamorphosis is achieved by the temporal regulation of glucose metabolism by steroid hormones in Drosophila.
Abstract
A simple geometric mechanism: ‘the locus of intersections of perpendicular bisectors and normal lines’, often arises in many guises in nonlinear sciences. In this paper, a new application of ...this simple geometric mechanism is given. Namely, we show that this mechanism gives answers to all four basic problems on envelopes created by hyperplane families (existence problem, representation problem, equivalence problem of definitions, uniqueness problem) at once.
The insulin-like peptide (ILP) family plays key biological roles in the control of body growth. Although the functions of ILPs are well understood, the mechanisms by which organisms sense their ...nutrient status and thereby control ILP production remain largely unknown. Here, we show that signaling relay and feedback mechanisms control the nutrient-dependent expression of Drosophila ILP5 (Dilp5). The expression of dilp5 in brain insulin-producing cells (IPCs) is negatively regulated by the transcription factor FoxO. Glia-derived Dilp6 remotely regulates the FoxO activity in IPCs, primarily through Jeb secreted by cholinergic neurons. Dilp6 production by surface glia is amplified by cellular response to circulating Dilps derived from IPCs, in concert with amino acid signals. The induction of dilp5 is critical for sustaining body growth under restricted food conditions. These results provide a molecular framework that explains how the production of an endocrine hormone in a specific tissue is coordinated with environmental conditions.
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•Nutrient-dependent dilp5 expression is negatively regulated by FoxO in brain IPCs•FoxO activity is regulated by Alk, and its ligand Jeb is secreted by cholinergic neurons•Glia-derived Dilp6 remotely initiates dilp5 expression through cholinergic neurons•The induction of dilp5 is critical to sustain body growth under restricted food
Insulin-like peptides (ILPs) play key roles in the control of body growth in response to nutrient status. Okamoto and Nishimura now demonstrate the signaling relay and feedback mechanisms by which insulin-producing cells sense nutritional signals and thereby control the production of an ILP in the fruit fly Drosophila melanogaster.
The evolution of the organic insulated power module and technology of high thermal conductivity and high heat resistance of the key material, which is the Thermally Conductive Electrically Insulating ...Layer (TCIL), have been reported. TCIL is a polymer / ceramic composite material filled with thermally conductive filler of ceramics in thermosetting resin. Due to the evolution of TCIL and utilization of bonding function that is characteristic of thermosetting resin, the heat dissipation performances have been greatly improved and the downsizing and higher power density of organic insulated module were achieved. Innovations on high performance polymer materials are expected to further improve the performance of power modules in the future.
Evolutionarily conserved insulin/insulin-like growth factor (IGF) signaling (IIS) correlates nutrient levels to metabolism and growth, thereby playing crucial roles in development and adult fitness. ...In the fruit fly Drosophila, ImpL2, an ortholog of IGFBP7, binds to and inhibits the function of Drosophila insulin-like peptides. In this study, we isolated a temperature-sensitive mutation in the insulin receptor (InR) gene as a spontaneous revertant in ImpL2 null mutants. The p.Y902C missense mutation is located at the functionally conserved amino acid residue of the first fibronectin type III domain of InR. The hypomorphic InR mutant animals showed a temperature-dependent reduction in IIS and body size. The mutant animals also exhibited metabolic defects, such as increased triglyceride and carbohydrate levels. Metabolomic analysis further revealed that defects in InR caused dysregulation of amino acid and ribonucleotide metabolism. We also observed that InR mutant females produced tiny irregular-shaped embryos with reduced fecundity. In summary, this novel allele of InR is a valuable tool for the Drosophila genetic model of insulin resistance and type 2 diabetes.
Implantable VAD Treatment as Out Patient Nishimura, Takashi
Transactions of Japanese Society for Medical and Biological Engineering,
2021, Letnik:
Annual59, Številka:
Abstract
Journal Article
Recenzirano
Odprti dostop
Implantable VAD treatment has already been provided to more than 1,500 patients, and the results are extremely good. However, the frequency of cases with a period of less than one year until the ...first readmission is as high as 60% or more. Even though, their complications can be fatal, it is believed that early response is the reason why the survival rate is better than the incidence. To overcome this, several biomedical engineering approaches are being reported. One of them is "transcutaneous energy transfer" that eliminates the skin penetration of the drive cable, which is the gateway to infection and has already started clinical use overseas. The other is "remote monitoring" which aims to quickly detect and respond to abnormalities in pumps and patients by the new communication environment, AI, etc. It is expected that medical engineering will continue to play a major role in home VAD treatment.
Adapting to changes in food availability is a central challenge for survival. Glucose is an important resource for energy production, and therefore many organisms synthesize and retain sugar storage ...molecules. In insects, glucose is stored in two different forms: the disaccharide trehalose and the branched polymer glycogen. Glycogen is synthesized and stored in several tissues, including in muscle and the fat body. Despite the major role of the fat body as a center for energy metabolism, the importance of its glycogen content remains unclear. Here, we show that glycogen metabolism is regulated in a tissue-specific manner under starvation conditions in the fruit fly
The mobilization of fat body glycogen in larvae is independent of Adipokinetic hormone (Akh, the glucagon homolog) but is regulated by sugar availability in a tissue-autonomous manner. Fat body glycogen plays a crucial role in the maintenance of circulating sugars, including trehalose, under fasting conditions. These results demonstrate the importance of fat body glycogen as a metabolic safeguard in
.
Abstract
We examined the effect of applying a static magnetic field on the formation of a silicon (Si) protrusion, which was grown on a narrow path of a Si wafer by surface melting of the path via ...resistive-current heating and re-solidification upon cooling. In the absence of the magnetic field, the surface-melted Si accumulated locally on the narrow path, and a Si protrusion formed upon cooling. In a magnetic field of 0.1 T, a higher and sharper protrusion is formed under an appropriate configuration of the field and current direction. Under the magnetic field, the Lorentz force probably acted on the surface-melted Si through the heating current to draw melted Si in the growth direction of the protrusion. This study demonstrates that the application of a magnetic field is effective for controlling the flow of surface-melted Si and the shape of the Si protrusions via resistive-current heating.
Abstract
Si protrusions were fabricated by surface melting and resolidifying of a Si(111) wafer covered with a 100 nm thick molybdenum (Mo) layer, in which a narrow region was generated using a ...microgrinder. This region results in a narrow current path and thus localized resistive heating, leading to specific melting of the Si in the path. The melted Si flowed away from the path to both sides, which were at temperatures lower than that of the path. Consequently, two Si protrusions ∼400
μ
m in height capped with Mo silicide precipitates were formed on each side of the burned-out path, as revealed by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The formation mechanism was discussed in terms of the non-uniform temperature, surface tension, interdiffusion, and freezing-point depression of the surface. This study revealed the potential of fabricating an array of self-assembled Si protrusions by resistive heating of narrow paths.
Trehalose is a non-reducing disaccharide that serves as the main sugar component of haemolymph in insects. Trehalose hydrolysis enzyme, called trehalase, is highly conserved from bacteria to humans. ...However, our understanding of the physiological role of trehalase remains incomplete. Here, we analyze the phenotypes of several Trehalase (Treh) loss-of-function alleles in a comparative manner in Drosophila. The previously reported mutant phenotype of Treh affecting neuroepithelial stem cell maintenance and differentiation in the optic lobe is caused by second-site alleles in addition to Treh. We further report that the survival rate of Treh null mutants is significantly influenced by dietary conditions. Treh mutant larvae are lethal not only on a low-sugar diet but also under low-protein diet conditions. A reduction in adaptation ability under poor food conditions in Treh mutants is mainly caused by the overaccumulation of trehalose rather than the loss of Treh, because the additional loss of Tps1 mitigates the lethal effect of Treh mutants. These results demonstrate that proper trehalose metabolism plays a critical role in adaptation under various environmental conditions.
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